/Engine/Source/Runtime/Online/ICMP/Public/Icmp.h
The third argument is a callback function that will be invoked on the game thread after all replies are received, timed out, or otherwise terminated (e.g. remote address could not be resolved, host unreachable, send failed, etc.). It passes aFIcmpEchoManyCompleteResultinstance, containing the overall completion status, and the ping results obtained so far for all of the supplied targets.
static void UDPEchoMany ( const [TArray](API\Runtime\Core\Containers\TArray)< [FIcmpTarget](API\Runtime\Icmp\FIcmpTarget) > & Targets, float Timeout, FIcmpEchoManyCompleteDelegate CompletionDelegate )